1. Field of the Invention
This invention relates to a communication checker for checking the wireless communication state between devices, a communication-state detection system and a method for checking the communication state, more particularly, to a communication checker for checking the communication state of a master unit communicating with a plurality of slave units or the slave units, a communication-state detection system and a method for checking the communication state.
2. Description of the Related Art
FIG. 6 is a block diagram showing a structure of a wireless communication system. By referring to FIG. 6, this wireless communication system includes slave units 30a to 30c that are connected to a predetermined measuring instrument and transmits the data from the instrument, a master unit 20 that receives the data transmitted from the slave units 30a to 30c, and a management server 40 that manages the data transmitted from the master unit 20. The communication between the slave units 30a to 30c and the master unit 20 can be conducted through specified low power radio (hereinafter referred to as “SLPR”) service, while the communication between the master unit 20 and the management server 40 is conducted through Freedom of Mobile Multimedia Access (hereinafter referred to as “FOMA”) (trademark, the rest is omitted) service, which is a mobile cellular telecommunication system. Thus, the master unit 20 includes an SLPR communication unit 21 to use the SLPR service and a FOMA communication unit 22 to use the FOMA service.
Such a communication system using the different communication services requires the master unit 20 to be installed at a position where both services deliver high-performance communication.
Conventional apparatuses for evaluating the communication state in wireless communications are disclosed in, for example, Japanese unexamined patent publication Nos. 2004-280793 and 2001-168783. Publication No. 2004-280793 discloses a method in which a personal computer evaluates the strength of signals transmitted from wireless computer peripheral devices.
Alternatively, publication No. 2001-168783 discloses an apparatus for checking an error rate to readily locate an installation site for a repeater that makes up a network.
There are not any other methods for detecting communication states except for the techniques, as described above, which cannot readily detect positions where both the services deliver high-performance communication with the communication system as shown in FIG. 6, thus involving a difficulty in determining where the master unit ought to be set up.